String.prototype.trim = function() {
     return this.replace(/(^\s*)|(\s*$)/g, '');
}

String.prototype.startWith = function(str){     
  var reg=new RegExp("^"+str);     
  return reg.test(this);        
}  

String.prototype.endWith = function(str){     
  var reg=new RegExp(str+"$");     
  return reg.test(this);        
}

String.prototype.formatCurrency = function() {
    var num = this.replace(/\$|\,/g,'');
    if(isNaN(num))
    num = "0";
    sign = (num == (num = Math.abs(num)));
    num = Math.floor(num*10+0.50000000001);
    cents = num%10;
    num = Math.floor(num/10).toString();
    for (var i = 0; i < Math.floor((num.length-(1+i))/3); i++)
    num = num.substring(0,num.length-(4*i+3))+','+
    num.substring(num.length-(4*i+3));
    return (((sign)?'':'-') + num + '.' + cents);
}